Power cable for high temperature environments

RELATED APPLICATION

This application claims priority to and is a continuation of application Ser. No. 12/333,289, filed on Dec. 11, 2008.

BACKGROUND

This section provides background information to facilitate a better understanding of the various aspects of the invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

Power cables are utilized in various applications to transmit power, such as electricity, between distal locations. For example, power cables are utilized to transmit electrical power to electric submersible pumps (ESPs). ESPs and power cables that are deployed in wellbores, for example, may encounter high temperatures which degrade convention power cables resulting in the premature failure of the power cables.

SUMMARY

According to one or more embodiments, an electric power cable for high temperature environments includes an electric conductor; an electrical insulator disposed on the electric conductor to form an insulated conductor, the electrical insulator suited for operation in a high temperature environment; and a protective sheath disposed over the insulated conductor to form a sheathed conductor.

According to one or more aspects of the invention, an electrical power cable for high temperature environments comprises two or more sheathed conductors; each sheathed conductor comprising an electrical conductor, an electrical insulator surrounding the electrical conductor, and a sheath surrounding the electrical insulator; and a bonding material interconnecting the sheaths of the two or more sheathed conductors positioned adjacent to one another to form a cable. The cable may be formed in a planar or non-planar shape. In some embodiments the cable does not include an outer layer interconnecting the two or more sheathed conductors.

An illustrative embodiment of a wellbore installation according to one or more aspects of the invention includes an electric submersible pump (ESP) deployed in the wellbore; and a power cable extending between the ESP and a distal electric power source, the power cable comprising: two or more sheathed conductors, each sheathed conductor comprising an electrical conductor, an electrical insulator surrounding the electrical conductor, and a sheath surrounding the electrical insulator; and a bonding material interconnecting the sheaths of the two or more sheathed conductors positioned adjacent to one another to form a cable.

The foregoing has outlined some of the features and technical advantages of the invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

<figref idref="DRAWINGS">FIG. 1</figref> is a well schematic illustrating and electric submersible pump and power cord according to one or more aspects of the invention deployed in a wellbore.

<figref idref="DRAWINGS">FIG. 2</figref> is an illustration of an embodiment of a power cable according to one or more aspects of the invention.

<figref idref="DRAWINGS">FIG. 3</figref> is an illustration of another embodiment of a power cable according to one or more aspects of the invention.

<figref idref="DRAWINGS">FIG. 4</figref> is an illustration of another embodiment of a power cable according to one or more aspects of the invention.

<figref idref="DRAWINGS">FIG. 5</figref> is an illustration of a non-planar embodiment of a power cable according to the disclosure.

<figref idref="DRAWINGS">FIG. 6</figref> is an illustration of a non-planar embodiment of a power cable according to the disclosure.

<figref idref="DRAWINGS">FIG. 7</figref> is an illustration of a non-planar embodiment of a power cable according to the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.

<figref idref="DRAWINGS">FIG. 1</figref> is a well schematic illustrating an electric submersible pump, generally denoted by the numeral <b>10</b>, deployed in a wellbore <b>12</b>. In the embodiment illustrated in <figref idref="DRAWINGS">FIG. 1</figref>, ESP <b>10</b> includes an electric motor <b>14</b>, a motor protector <b>16</b> and a pump <b>18</b>. Pump <b>18</b> is fluidly connected to the surface <b>20</b> via a production conduit <b>22</b>. A power cable <b>24</b> is connected between an electrical power source <b>26</b> and pump <b>18</b>.

Refer now to <figref idref="DRAWINGS">FIG. 2-4</figref> wherein embodiments of power cable <b>24</b> that are adapted for use in high temperature environments are illustrated. It is perceived that power cable <b>24</b> is suited for installation in environments wherein the temperature is continuously in the range of about 500 degrees Fahrenheit (260 degrees Celsius). It is perceived that power cable <b>24</b> can withstand temperatures in excess of 500 degrees F. for extended lengths of times without significant degradation as needed for installations such as a wellbore deployed ESP.

Power cable <b>24</b> may include one or more electrical conductors. In the illustrated embodiments, power cable <b>24</b> includes three electrical conductors <b>28</b>. Each conductor <b>28</b> is surrounded with an electrical insulation <b>30</b> and a protective sheath <b>32</b>. The two or more of the insulated and sheath conductors are then interconnected to form cable bundle.

Refer now to <figref idref="DRAWINGS">FIG. 2</figref> wherein an embodiment of power cable <b>24</b> is illustrated. Power cable <b>24</b> is illustrated as having three electrical conductors <b>28</b> formed of copper. In this embodiment, insulator <b>30</b> includes at least two layers (<b>30</b><i>a</i>, <b>30</b><i>b</i>) of insulating material. The insulating layers may be formed of the same or different material. In one example, one insulating layer may be a high temperature dielectric tape and the other layer may be dielectric tape or extruded material.

In the embodiment of <figref idref="DRAWINGS">FIG. 2</figref>, the two layers are formed of different material each of which is suited for continuous exposure of temperature of 500 degrees F. and greater. In this example, first insulating layer <b>30</b><i>a </i>is a dielectric material such as and without limitation polyimide. Polyimide layer <b>30</b><i>a </i>is a tape helically wrapped about conductor <b>28</b>. Second insulating layer <b>30</b><i>b </i>may be a dielectric material such as without limitation a fluoropolymer tape or an extruded fluoropolymer layer. In one embodiment the fluoropolymer is selected from a group including polytetrafluoroethylene or polytetrafluoroethene (PTFE), fluorinated ethylene propylene (FEP), or perfluoroalkoxy (PFA). If more than one layer of tape is utilized, the layer may be helically wrapped in the same direction or in opposite directions. The material may include an adhesive on one or both sides for bonding to the conductor, itself, other layers of insulating material and the like.

Protective sheath <b>32</b> is disposed over the insulated conductor <b>28</b>. Sheath <b>32</b> is constructed of a material suited for protecting the insulated conductor <b>28</b> in the environment in which it is deployed. For example, sheath <b>32</b> in the illustrated embodiments is constructed of a material that can provide physical protection to conductor <b>28</b> in a wellbore environment and in a high temperature environment. In some embodiments, sheath <b>32</b> is constructed of a metallic material such as without limitation stainless steel, MONEL, carbon steel, lead or the like.

The insulated and sheathed conductors <b>28</b> are interconnected to form a power cable <b>24</b> suited for the particular service. In the embodiment of <figref idref="DRAWINGS">FIG. 2</figref>, insulated and sheathed conductors <b>28</b> are interconnected by wrapping with an outer layer of material <b>34</b>. Outer layer <b>34</b>, referred to from time to time as armor layer <b>34</b>, may be constructed of a metallic or non-metallic material. In <figref idref="DRAWINGS">FIG. 2</figref>, conductors <b>28</b> are shown positioned and interconnected to form a planar power cable <b>24</b>. However, it should readily be recognized that conductors <b>28</b> may be positioned relative to each other in a variety of manners. For example, interconnected conductors <b>28</b> may form a triangular or cylindrically shaped power cable <b>24</b>.

Refer now to <figref idref="DRAWINGS">FIG. 3</figref>, wherein another embodiment of a power cable <b>24</b> is illustrated. This embodiment is substantially similar in construction as that described with reference to <figref idref="DRAWINGS">FIG. 2</figref>. One difference between this described embodiment and the prior described embodiment is that the insulated and sheathed conductors <b>28</b> are bonded together and do not include an outer layer interconnecting conductors <b>28</b>. For example, and without limitation, insulated and sheathed conductors <b>28</b> may be interconnected by welding or an adhesive material illustrated generally by the numeral <b>36</b>. For example, in this embodiment sheaths <b>32</b> are metallic and sheaths <b>32</b> are interconnected by bonding at bead <b>36</b>.

Referring now to <figref idref="DRAWINGS">FIG. 4</figref>, another embodiment of power cable <b>24</b> is illustrated. In this embodiment it is clearly shown that each conductor <b>28</b> is insulated with a single layer of insulating material <b>30</b>. Sheath <b>32</b> is then disposed over insulating layer <b>30</b> and conductor <b>28</b> as further described with reference to <figref idref="DRAWINGS">FIGS. 2 and 3</figref>. Sheathed conductors <b>28</b> may then be interconnected to form power cable <b>24</b>.

Referring now to <figref idref="DRAWINGS">FIG. 5</figref>, a non-planar embodiment of power cable <b>24</b> is illustrated. Specifically, this embodiment presents a triangular shaped power cable <b>24</b> wherein the conductors <b>28</b> are each insulated with a layer of insulating material <b>30</b>. However, it should be recognized that more than one layer of insulating material may be used, e.g., as shown in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>. A sheath <b>32</b> is disposed over the insulating layer <b>30</b> and conductor <b>28</b>. The sheathed conductors may be interconnected and covered by outer layer <b>34</b> to form power cable <b>24</b>.

Referring now to <figref idref="DRAWINGS">FIG. 6</figref>, a non-planar embodiment of power cable <b>24</b> is illustrated. Specifically, this embodiment presents a triangular shaped power cable <b>24</b> wherein the conductors <b>28</b> are each insulated with a layer of insulating material <b>30</b>. However, it should be recognized that more than one layer of insulating material may be used, e.g., as shown in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>. A sheath <b>32</b> is disposed over the insulating layer <b>30</b> and conductor <b>28</b>. The sheathed conductors may be interconnected and covered by bead of welding or adhesive material <b>36</b> to form power cable <b>24</b>.

Referring now to <figref idref="DRAWINGS">FIG. 7</figref>, a non-planar embodiment of power cable <b>24</b> is illustrated. Specifically, this embodiment presents a triangular shaped power cable <b>24</b> wherein the conductors <b>28</b> are each insulated with a layer of insulating material <b>30</b>. However, it should be recognized that more than one layer of insulating material may be used, e.g., as shown in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>. A sheath <b>32</b> is disposed over the insulating layer <b>30</b> and conductor <b>28</b>. The sheathed conductors may be interconnected and covered by bead of welding or adhesive material <b>36</b> and by outer layer <b>34</b> to form power cable <b>24</b>.

From the foregoing detailed description of specific embodiments of the invention, it should be apparent that a system for a high temperature power cable that is novel has been disclosed. Although specific embodiments of the invention have been disclosed herein in some detail, this has been done solely for the purposes of describing various features and aspects of the invention, and is not intended to be limiting with respect to the scope of the invention. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the disclosed embodiments without departing from the spirit and scope of the invention as defined by the appended claims which follow.